In article , Michael Press wrote:

Is there a standard definition of what it means to S2S?

Surfaced 2 Sides. Usually means planed both sides.

Standard technique to get 2 faces surfaced is to joint an edge, then
joint a face, then plane the opposite face. Thus to S2S such that a
board is flat, you've really S3S (or S2S1E as I've seen used).

If you want your lumber jointed, you must specify it that way, and likely pay
a good bit extra. S2S does *not* mean jointed on one face and planed on the
other.

Seems to me that if you just S2S you've got 2 faces parallel but the
board isn't necessarily flat - it could have a bow or twist that isn't
removed by planing the 2 faces.

That is correct. For that reason, I buy my lumber rough whenever I can, and
joint and plane it myself.

So what I really want to know is ... is S2S lumber flat enough for
precision work without further flattening, such as to make a picture
frame or cabinet door frame?

No.

If not, is S4S any flatter?

Why would it be? That just means the edges are approximately straight, and
approximately square to the faces.

--
Doug Miller (alphageek at milmac dot com)

How come we choose from just two people to run for president and 50 for Miss America?